Combined Heat and Power (CHP) & Boiler

The templates consists of various configurations of a CHP combined with a boiler.

CHP & Boiler - Parallel

Working principle

The programmable controller controls the CHP, visualised in the figure below. It gives the setpoint to the external PI-controller for regulating the 3-way valve on the setpoint return temperature. Internally it will enable or disable the CHP and it will calculate the modulation based on the measured return temperature.

The boiler is activated when the flow temperature of the system drops under 73°C, and deactivated when the flow temperature rises over 77°C. The activation also includes a check for the minimal flow rate, if the flow rate through the system is insufficient, the boiler won’t be activated. For instance, if the installation is shut down, the temperatures in the pipes will drop but the boiler won’t be activated because there is no flow through the system. During the activation of the boiler, an isolation valve at the boiler will open.

Controls

More information about the controls of the CHP can be found in Combined Heat and Power (CHP).

Notices/Remarks

The system can be further optimised by doing sensitivity studies. For instance, a sensitivity study can be done for the size of the storage vessel or the thermal power of the CHP. To change the thermal power, the user should change the power spread found in the hybrid production configuration BC. More information about hybrid production configurations can be found in Hybrid production Heating.
The user should lock the nominal thermal power and return temperature of the CHP. If not, the software will calculate with the propagated power and return temperature from the installation.

When using a thermal energy storage vessel, the user should lock the temperature regime of the CHP. If not, the software will calculate with the propagated power and return temperature from the installation. The locked temperature regime is visualised in the figure below.

It is possible to upload electrical and thermal efficiency tables, by clicking on the pencil icon. The user can download an example file by clicking on the gray arrow icon. After adjusting this file, the user can upload it back to the CHP by clicking on the blue arrow icon.

The user can change the design temperatures, thermal power, end units, … But keep in mind that the controls have to be changed as well. This can be done by changing the “settings” in the programmable controller which are listed in the top of the code. After changes in the settings, the correct operation has to be checked again. The user should only change the “settings” and nothing else in the code to make sure the correct control strategy is still valid.
If the user changes the power of the end-units the thermal capacity of the boiler and CHP doesn’t change automatically. The user should implement a correct capacity corresponded with the thermal power of the production units.

More information about the CHP and boiler can be found in CHP (Combined Heat & Power) and Condensing boiler.

CHP & Boiler - Reverse shunt in return

Idem as the template “CHP & Boiler - Parallel”, except for the shunt configuration instead of the parallel configuration. There is also a bypass valve to bypass the boiler when the boiler is deactivated.